Frequency tuining of a rf-generator within a plasma process

Abstract

The invention describes a method of frequency tuning an electrical generator (100) for supplying electrical power to a plasma, wherein the method comprises a pulsed mode, the pulse mode comprising at least a high power pulse (314) comprising a high power level (304) and a low power pulse (312) comprising a low power level (302) different to zero power, the method comprising the steps of: --providing RF-power with a high power starting frequency set comprising at least one high power starting frequency (502, 504, 506) at the high power pulse (314) with a predefmed high power pulse shape; --providing RF-power with a low power starting frequency set comprising at least one low power starting frequency (512, 514) at the low power pulse (312) with a predefmed low power pulse shape; --determining a reflected high power at the high power starting frequency (502, 504, 506); --tuning the high power starting frequency (502, 504, 506) to a different first high power frequency if the reflected high power exceeds a high power threshold value such that the reflected high power decreases below the high power threshold value; --determining a reflected low power at the low power starting frequency (512, 514); --tuning the low power starting frequency (512, 514) to a different first low power frequency if the reflected low power exceeds a low power threshold value such that the reflected low power decreases below the low power threshold value. The invention further describes a corresponding electrical generator (100), plasma processing system and computer program product. The method, the electrical generator, the plasma processing system and the computer program product may have the advantage that the stability of the plasma with respect to repeated and essentially identical high and low power pulses is used to reduce the controlling effort and to check the stability of the plasma process.

Description

FIELD OF THE INVENTION[0001]The invention relates to a method of frequency tuning, a related electrical generator and plasma processing system and a corresponding computer program product.BACKGROUND OF THE INVENTION[0002]US 2009 / 0284156 A1 discloses methods of tuning a plasma process and corresponding apparatus which may include an RF power supply having frequency tuning and a matching network coupled to the RF power supply that share a common sensor for reading reflected RF power reflected back to the RF power supply and a common controller for tuning each of the RF power supply and the matching network.[0003]The proposed methods and corresponding apparatus are complex.SUMMARY OF THE INVENTION[0004]It's thus an object according to a first aspect of the present invention to provide an improved method of frequency tuning a plasma process.[0005]According to a first aspect a method of frequency tuning an electrical generator for supplying electrical power to a plasma is provided. The m...

AI Technical Summary

Benefits of technology

The patent describes a method and system for generating high and low power pulses in a plasma chamber. The system uses a tuning process to minimize reflected power during pulses. The high or low power pulses can be adjusted based on the previous step to determine the optimal frequency set. The system can also adapt the frequency sets as the impedance of the plasma changes over time. This method and system may be useful for checking the stability of the plasma process and reducing the control effort with repeated pulses.

Problems solved by technology

The proposed methods and corresponding apparatus are complex.

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